[Tommy]

This may not be the best suggestion you get, but here goes. If you know which side of the track the microphone is on, direct both exhausts out the other side. That means a rework of the exhaust system, possibly more weight, and maybe changing it from track to track. I don't know of another solution to reduce sound levels without inhibiting engine performance. .... Maybe you could rotate the end piece on the sidepipe nearest the microphone to direct the exhaust more under the car than outward. But keep the gases out of the cockpit.